Results of experimental electromagnetic studies of the Crimean region

Abstract

Spatial-temporal pattern of distribution of geomagnetic variations and the electric field on the Earth’s surface was obtained as a result of the modern experimental observations conducted in 2007—2013 along 9 profiles (48 points) by the methods of magnetotelluric sounding (MTS) and magnetovariation profiling (MVP). These profiles cross various geological structures of the Crimean region. It is possible to estimate the value of the electrical conductivity and vertical and horizontal geoelectric structure. The processing of these data is done using modern software system PRC_MTMV (author Varentsov Iv. M.) that provides the common noise-protected evaluation of the impedance, tipper, horizontal magnetovariation response according to the synchronous MT/MV records.

The main result of qualitative interpretation of geoelectric research is the detection of high conductivity regions in the Earth's crust and upper mantle of the Crimea,that are characterized by the variations of conductivity, depth and configuration. They characterize the various geological structures differently. The subvertical conductive zones often coincide with the fault structures, most of these objects areconfined to the suture zones between tectonic elements such as the East European platform and the Scythian plate, the Scythian plate and the Crimea mountain, North and South Kerch zone. This fact may reflect the high permeability of thesuture zones for deep fluids in the process of their formation.

Some high conductivity anomalies are well-described in the literature and are known. For example, the unique Tarhankut conductivity anomaly, located not only on the eponymous peninsula of Crimea, but also under the water area of the north-western part of the Black sea. This anomaly was detailed and precised and involves a complex multi-level deep structure of the region. In addition, the structurally complex conductivity anomaly is assumed in the Sivash graben and the Kerch Peninsula.

Although the qualitative interpretation of the experimental data of magnetotelluric sounding (MTS) and magnetovariation profiling (MVP) provides the inconsistent understanding of the depth distribution of the Crimean region electrical conductivity, the combination of these methods allows to construct the model of the resistivity distribution within a three-dimensional environment much more accurately and adequately to the observed experimental data.